Disclosed is an electrochemical method for high-temperature molten salt electrolysis in humid atmosphere. The method involves preparing hydrogen gas, metals/alloys, metal oxide compounds and metal hydrides in humid high-temperature molten salt environment. Hydrogen gas is generated by electrolyzing water in a molten salt electrolyte at above 100 C., and with a working cathode being a solid-state oxide pellet and a voltage applied to the electrolyzing cell being far lower than that in a direct electro-deoxidation process, the hydrogen gas generated reduces solid-state oxide cathodes to produce metals. The hydrogen ions in the molten salt can be prepared by hydrolysis reaction of the molten salt in a water vapor containing atmosphere. Corresponding metals or alloys or metal oxide compounds can be prepared by reducing iron oxide, molybdenum oxide, tantalum oxide, nickel oxide, copper oxide, titanium oxide or corresponding compound oxides and the like.

An object of the present invention is to provide a Mn-based alloy exhibiting metamagnetism over a wide temperature range. A MnAl alloy according to the present invention exhibits metamagnetism and has crystal grains containing a -MnAl phase and crystal grains containing a 2-MnAl phase. Assuming that the area of the crystal grains containing the -MnAl phase in a predetermined cross section is B, and the area of the crystal grains containing the 2-MnAl phase therein is A, the value of B/A is 0.2 or more and 21.0 or less. When the ratio of the areas between the crystal grains containing the -MnAl phase and those containing the 2-MnAl phase is controlled within the above range, metamagnetism is imparted to the MnAl alloy and, thus, it is possible to obtain metamagnetism over a wide temperature range, particularly, over a temperature range of 100 C. to 200 C.

Disclosed is an electrochemical method for high-temperature molten salt electrolysis in humid atmosphere. The method involves preparing hydrogen gas, metals/alloys, metal oxide compounds and metal hydrides in humid high-temperature molten salt environment. Hydrogen gas is generated by electrolyzing water in a molten salt electrolyte at above 100 C., and with a working cathode being a solid-state oxide pellet and a voltage applied to the electrolyzing cell being far lower than that in a direct electro-deoxidation process, the hydrogen gas generated reduces solid-state oxide cathodes to produce metals. The hydrogen ions in the molten salt can be prepared by hydrolysis reaction of the molten salt in a water vapor containing atmosphere. Corresponding metals or alloys or metal oxide compounds can be prepared by reducing iron oxide, molybdenum oxide, tantalum oxide, nickel oxide, copper oxide, titanium oxide or corresponding compound oxides and the like.

A method for separating metal components from a treatment material containing a silicate and metal elements includes: a reaction step of reacting the treatment material and a molten alkali hydroxide in which bubbles due to water vapor derived from water are generated by heating a hydroxide of an alkali metal or an alkaline-earth metal and the water in a state where the hydroxide and the water coexist, to obtain a reaction product; and a first precipitation step of dissolving the reaction product of the treatment material and the molten alkali hydroxide after the reaction step in water, thereby generating a precipitate containing the metal elements.

A method of producing manganese metal or EMD by leaching a source of manganese with a solution comprising sulfuric acid to form a leach solution, adding one or more sulfides generated in a sulfide recycle stage to the leach solution in order to form sulfide precipitates comprising heavy metal sulfides, removing the sulfide precipitates from the leach solution, feeding the leach solution to one or more electrolytic cells, subjecting the purified leach solution to electrolysis so as to deposit manganese metal or EMD, reacting the sulfide precipitates with an acid to generate H.sub.2S, producing one or more sulfides from the H.sub.2S for recycle. Methods of producing manganese metal and a purified manganese sulfate solution are also provided.

In a method for removing a substance from a feedstock comprising a solid metal or a solid metal compound, the feedstock is contacted with a fused-salt melt. The fused-salt melt contains a fused salt, a reactive-metal compound, and a reactive metal. The fused salt comprises an anion species which is different from the substance, the reactive-metal compound comprises the reactive metal and the substance, and the reactive metal is capable of reaction to remove at least some of the substance from the feedstock. A cathode and an anode contact the melt, and the feedstock contacts the cathode. An electrical current is applied between the cathode and the anode such that at least a portion of the substance is removed from the feedstock. During the application of the current, a quantity of the reactive metal in the melt is maintained sufficient to prevent oxidation of the anion species of the fused salt at the anode. The method may advantageously be usable for removing the substance from successive batches of the feedstock, where the applied current is controlled such that the fused-salt melt after processing a batch contains the quantity of the reactive metal sufficient to prevent oxidation of the anion species at the anode.

In a method for removing a substance from a feedstock comprising a solid metal or a solid metal compound, the feedstock is contacted with a fused-salt melt. The fused-salt melt contains a fused salt, a reactive-metal compound, and a reactive metal. The fused salt comprises an anion species which is different from the substance, the reactive-metal compound comprises the reactive metal and the substance, and the reactive metal is capable of reaction to remove at least some of the substance from the feedstock. A cathode and an anode contact the melt, and the feedstock contacts the cathode. An electrical current is applied between the cathode and the anode such that at least a portion of the substance is removed from the feedstock. During the application of the current, a quantity of the reactive metal in the melt is maintained sufficient to prevent oxidation of the anion species of the fused salt at the anode. The method may advantageously be usable for removing the substance from successive batches of the feedstock, where the applied current is controlled such that the fused-salt melt after processing a batch contains the quantity of the reactive metal sufficient to prevent oxidation of the anion species at the anode.

Systems and methods for recovery of gaseous substances from molten salt electrolysis are generally described. Certain systems comprise a cell configured for molten salt electrolysis; a collector fluidically connected to the cell and configured to collect volatilized molten salt from the cell; and a gas scrubber fluidically connected to the collector and configured to at least partially remove a gas from an effluent stream of the cell. Some methods comprise, using a pressure gradient: transporting a gas comprising molten salt vapor from an electrolytic cell to and through a collector such that at least a portion of the molten salt vapor forms a solid within the collector; and transporting some or all of the gas from the collector through a gas scrubber.

The present invention relates to a method of recovering one or more metal species from a raw material, such as waste lithium-ion battery material comprising: providing a molten salt comprising at least one metal hydroxide, providing one or more oxoacidity agents, preferably as a reservoir of one or more oxoacidity agents being in communication with the molten salt, setting the oxoacidity of the molten salt with the one or more oxoacidity agents to an oxoacidity value to dissolve at least one metal species in the molten salt, contacting the raw material with the molten salt, performing at least one of the steps b) and c): b) setting an electrical potential of the molten salt to recover a first metal species to a first metal or first metal oxide, c) adjusting the oxoacidity of the molten salt with the one or more oxoacidity agents to precipitate a first metal oxide, d) optionally performing, for one or more further metal species, the method step a) and/or performing at least one of the method steps b) and c).

The present invention relates to a method of recovering one or more metal species from a raw material, such as waste lithium-ion battery material comprising: providing a molten salt comprising at least one metal hydroxide, providing one or more oxoacidity agents, preferably as a reservoir of one or more oxoacidity agents being in communication with the molten salt, setting the oxoacidity of the molten salt with the one or more oxoacidity agents to an oxoacidity value to dissolve at least one metal species in the molten salt, contacting the raw material with the molten salt, performing at least one of the steps b) and c): b) setting an electrical potential of the molten salt to recover a first metal species to a first metal or first metal oxide, c) adjusting the oxoacidity of the molten salt with the one or more oxoacidity agents to precipitate a first metal oxide, d) optionally performing, for one or more further metal species, the method step a) and/or performing at least one of the method steps b) and c).